Showing papers by "Bernt Krebs published in 1988"

Nickel-thiolate chemistry based on chelating ligands: controlling the course of self-assembly reactions via ligand bite distances. Synthesis, structures, and properties of the homoleptic complexes [Ni3(SCH2C6H4CH2S)4]2-, [Ni3(SCH2CH2S)4]2-, and [Ni6(SCH2CH2CH2S)7]2-

Abstract: Preparation et etude radiocristallographique des complexes du nickel. Determination du groupe d'espace, affinement des parametres structuraux et structures moleculaires decrivant les differents isomeres

Reaktive EC (p ? p) π‐Systeme, XIV. Synthese und Struktur von Phosphaalkenen des Typs F3CPC(F)NR2

Abstract: Perfluor-2-phosphapropen 1reagiert mit sekundaren Aminen R2NH im Molverhaltnis 1:2 bei Temperaturen zwischen −120 und −40°C quantitativ zu (Trifluormethyl) phosphaalkenen des typs F3CPC(F)NR2 [R = me(2), Et (3), i-Pr (4); NR2 = Pyrrolidino (5), Piperidino (6), 2-methylpiperidino (7), 3-Methylpiperidino (8), N-Methylanilino (9)]. diphenylamin Setzt sich selbst bei Raumtemperatur nicht in analoger Weise um. Zu den Gleichen Produkten gelangt man durch Umsetzung von (CF3)2PH mit R2NH bzw. R2NH/NEt3 im Molverhaltnis 1:3 bzw. 1:1 bzw. 1:1:2. Die neuen Verbindungen 4–9 sind wie 2 und 3 bei Raumtemperatur bestandig and besitzen ausnahmslos die Z-Konfiguration. Die Rontgenbeugungsanalyse des 1-(Dimethylamino)-1,3,3,3-tetrafluor-2-phospha-1-propens (2) beweist die beteiligung des freien Elektronenpaars am Stickstoff an der Stabilisierung des Systems. Das Gitter von 2. enthalt C4H6F4NP-Molekule mit fast planarem CPC(F)NC2-Gerust. Der PC-Bindungsabstand betragt 1.744 (2) A, der CN-Abstand ist mit 1.311(2)A 0.16A Kurzer als die CN Einfachbindungen in Aminen und zeigt eine Bindungsordnung nahe 2 an. Die Umsetzung von 2Mit Cr(CO)5(THF) liefert den Komplex CR(CO)5[F3PCC(F)NMe2] (10) mit P-Koordination. IN der Kristallstruktur von 10ist der CN-abstand des Koordinierten Liganden Geringfugig uber (1.29 A), der PC-Abstand deutlich groβer (1.80A) als in 2.10 wandelt sich bei 25°C unter Freisetzung von 2 langsam in den Zweikernkomplex [cr(CO)5]2F3CPC(F)NMe2 (11) um. Reactive EC (pp) π Systems, XIV. — Synthesis and Structure of Phosphaalkenes of the Type F3CPC(F)NR2 Perfluoro-2-phosphapropene 1reacts quantitatively with secondary amines R2NH in the molar ratio of 1:2 at temperatures between −120 and −40°C to give (trifluoromethyl)phosphaalkenes of the type F3CPC(F)NR2 R = Me (2), Et (3), i-pr (4); NR2 = pyrrolidino (5), piperidino (6), 2-methylpiperidino (7, 3-methylpiperidino (8), N-methylanilino (9). Diphenylamine does not react in the same way even at room temperature. The same products are obtained by teh reaction of (CF3)2PH with R2NH and R2NH/NEt3, respectively, in molar rations of 1:3 or 1:1:2. The new compounds 4–9 just as 2 and 3 are stable at room temperature and without exception have Z configuration. The X-ray structure analysis of 1-(dimethylamino)- 1,3,3,3-tetrafluoro-2-phospha-1propene (2) proves the participation of the lone pair on nitrogen in stabilizing the system. The lattice of 2 contains C4H6F4NP molecules with an almost planar CPC(F)NC2 skeleton. The PC bond distance amounts 1.744(2) A, the CN bond [1.311(2)A] is 0.16A shorter than CN single bonds in amines suggesting a bond order near 2. The reaction of 2With Cr(CO)5(THF) yields the complex Cr(CO)5[F3CPC(F)NMe2] (10) with P-coordination. In the crystal structure of 10 the CN distance of the coordination. In teh crystal structure of 10 the CN distance of the coordinated ligand is somewhat smaller (1.29 A) and is slowly transformed to give 2 and the binuclear complex [Cr(CO)5]2F3CPC(F)NMe2 (11)

Ortho-thioborates and ortho-selenoborates: synthesis, structure and properties of Tl3BS3 and Tl3BSe3

Abstract: Tl3BS3 (1) and Tl3BSe3 (2) were prepared as black crystalline phases by reaction of stoichiometric amounts of the elements at 800–950 °C and subsequent annealing at 400-200 °C. They are the first orthothio- and orthoselenoborates which have been characterized. According to single-crystal structure analyses, they contain trigonal planar BS33− (B-S bond length 1.83 A) and BSe33− groups (B-Se bond length 1.95 A). There are two structurally different thallium atoms in the structure with irregular 6 + 1- or 6 + 2-coordination by sulphur (selenium), the inert electron pair at Tl+ showing strong stereochemical activity. The crystal structures of 1 and 2 are isotypic to each other but not isotypic to any other M3AB3 structure. They are monoclinic, space group P2 1 m , with a = 5.444, b = 9.699, c = 6.690 A , β = 98.13δ for 1; and a = 5.547, b = 10.099, c = 6.852 A , β = 97.59° for 2, Z = 2. Vibrational spectra, mass spectra and thermoanalytic results for 1 and 2 are reported.

Two different copper(II) coordination geometries imposed by two closely related chelating imidazole-thioether (N2S2) ligands: crystal structures of (1,6-bis(4-imidazolyl)-2,5-dithiahexane)chlorocopper(II) tetrafluoroborate, (1,6-bis(5-methyl-4-imidazolyl)-2,5-dithiahexane)chloro(tetrafluoroborato)copper(II), and (1,6-bis(5-methyl-4-imidazolyl)-2,5-dithiahexane)nitrato(thiocyanato-N)copper(II)

Abstract: Le premier complexe cristallise dans le systeme triclinique avec le groupe d'espace P1 et sa structure est affinee jusqu'a 0,373. Les deuxieme et troisieme complexes cristallisent dans le systeme monoclinique avec le groupe d'espace P2 1 /n. Affinement de la structure jusqu'a 0,0325 et 0,047 respectivement

Neue Untersuchungen an α-Platindichlorid Darstellung und Struktur

Abstract: Durch Verbesserung der Synthese- und Transportbedingungen wurde α-PtCl2, die Hochtemperaturmodifikation des Platin(II)-chlorids, rein und in Form von Einkristallen dargestellt. Wie neue Experimente zeigen, kann auser Cl2 und Al2Cl6 auch Ga2Cl6 bzw. GaCl3 als Transportmittel zur Abscheidung von α-PtCl2 eingesetzt werden; hierbei bildet sich der Komplex PtGa2Cl8 in der Gasphase. Die in schwarzen Nadeln Kristallisierende Verbindung ist monoklin und bildet eine fehlgeordnete Struktur. Die Elementarzelle der Uberlagerungs-Substruktur kann in der Raumgruppe C2/m mit a = 13,258(3), b = 3,194(1), c = 6,802(2) A, β = 107,75(3)°, Z = 4 beschrieben werden. Die Strukturanalyse auf der Basis von Einkristall-Diffraktometerdaten zeigt parallel zur b-Achse verlaufende Doppelbander kanten- und/oder eckenverknupfter quadratisch-planarer PtCl4-Einheiten. Die relative Anordnung der (PtCl4/2)n-Doppelbander ist fehlgeordnet. α-PtCl2 ist nicht isotyp mit α-PdCl2. New Investigations on α-PtCl2: Preparation and Structure The high-temperature modification of platinum(II) chloride, α-PtCl2, was prepared in pure from as single crystals by improvements of the synthetic and transport procedures. The experiments show that Ga2Cl6 and GaCl3 can be employed besides Cl2 and Al2Cl6 as a transporting agent for the preparation of α-PtCl2; PtGa2Cl8 is formed in the transport process. The compound crystallizes in black needles and forms a disordered structure. The unit cell of the averaged substructure can be described in the space group C2/m with a = 13.258, b = 3.194, c = 6.802 A, β = 107.75°, Z = 4. The crystal structure analysis based on single crystal diffractometer substructure reflections shows double strings of edge- and/or corner-sharing square-planar PtCl4 units which are running parallel to the b axis. The arrangement of the strings relative to each other is disordered. α-PtCl2 is not isotypic with α-PdCl2.

Die Kristall‐ und Molekülstruktur von Mangan(VII)‐oxid

Abstract: Mn2O7 kristallisiert monoklin mit a = 679,56 pm, b = 1668,7 pm, c = 945,4 pm, β = 100,20°, Z = 8 in der Raumgruppe P21/c. Das Mn2O7-Molekul besteht aus zwei uber ein verbruckendes O-Atom verknupften MnO4-Tetraedern; der Bruckenwinkel MnOMn betragt 120,7°. Die Bindungsabstande MnO sind 177,0 pm (Brucke) sowie 2 × 160,0 pm und 158,5 pm im MnO4-Tetraeder. Im festen Zustand sind die Mn2O7-Molekule in einer Weise gepackt, das die Anordnung der O-Atome im Kristall einer kubisch dichtesten Kugelpackung entspricht, d. h. Mn2O7 last sich einfach als Defekt-anti-CaF2-Typ beschreiben. Die geometrischen Eigenschaften von Mn2O7 werden anderen Molekulstrukturen gegenuber-gestellt; insbesondere werden Mn2O7 und Tc2O7 bezuglich Struktur und Bindung verglichen. Crystal and Molecular Structure of Manganese (VII) Oxide Mn2O7 crystallizes in the monoclinic space group P21/c with a = 679.56 pm, b = 1668.7 pm, c = 945.4 pm, β = 100.20°, Z = 8. The Mn2O7 molecule consists of cornersharing pairs of MnO4 tetrahedra; the bridging MnOMn angle is 120.7°. The MnO bond lengths are 177.0 pm (bridge), 2 × 160.0 pm and 158.5 pm in the MnO4 tetrahedron. In the crystal the Mn2O7 molecules are packed in a way to yield the arrangement of a cubic close packing for the O atoms. Formally Mn2O7 can be described as a defect-anti-type of CaF2. We compare the geometrical properties of Mn2O7 with other molecular structures with an emphasis on the difference of structure and bonding between Mn2O7 and Tc2O7.

ortho-Thioborates and ortho-Selenoborates: Synthesis, Structure and Properties of Tl3BS3 and Tl3BSe3.

Abstract: Tl3BS3 (1) and Tl3BSe3 (2) were prepared as black crystalline phases by reaction of stoichiometric amounts of the elements at 800–950 °C and subsequent annealing at 400-200 °C. They are the first orthothio- and orthoselenoborates which have been characterized. According to single-crystal structure analyses, they contain trigonal planar BS33− (B-S bond length 1.83 A) and BSe33− groups (B-Se bond length 1.95 A). There are two structurally different thallium atoms in the structure with irregular 6 + 1- or 6 + 2-coordination by sulphur (selenium), the inert electron pair at Tl+ showing strong stereochemical activity. The crystal structures of 1 and 2 are isotypic to each other but not isotypic to any other M3AB3 structure. They are monoclinic, space group P2 1 m , with a = 5.444, b = 9.699, c = 6.690 A , β = 98.13δ for 1; and a = 5.547, b = 10.099, c = 6.852 A , β = 97.59° for 2, Z = 2. Vibrational spectra, mass spectra and thermoanalytic results for 1 and 2 are reported.